code: def _find_and_replace_alpha_spans(line):
      r"""
      传入原始句子，替换其中的字母为特殊标记
  
      :param str line:原始数据
      :return: str
      """
      new_line = ""
      pattern = "[a-zA-Z]+(?=[\u4e00-\u9fff ，％,.。！<－“])"
      prev_end = 0
      for match in re.finditer(pattern, line):
          start, end = match.span()
          span = line[start:end]
          new_line += line[prev_end:start] + _alpha_span_to_special_tag(
              span
          )
          prev_end = end
      new_line += line[prev_end:]
      return new_line
  
file_path: fastNLP/fastNLP/io/pipe/cws.py
imports: import re
  from itertools import chain
  from .pipe import Pipe
  from .utils import _indexize
  from fastNLP.io.data_bundle import DataBundle
  from fastNLP.io.loader import CWSLoader
label_desc: Use image node_id 4 for calling a global function with example usage: _find_and_replace_alpha_spans(line) and returns: new_line